Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?

Erklärung

Evaporation and the temperature inversion of warm air lying over cooler water create a sharp vertical gradient of refractive index that traps microwave energy in a thin layer near the surface. Mountain ranges obstruct a path rather than duct it, and cloud types are symptoms of air-mass structure rather than the refractive-index gradient itself.